Expandable dental implants of high surface area and methods of expanding the same

ABSTRACT

A dental implant system for placement within a jaw of a patient includes an envelope including an outer surface and an inner surface defining a barrel. At least one barrier is located in the barrel. The barrel having a first region on one side of the barrier and a second region on an opposing side of the barrier. An expander member is movable within the barrel along a longitudinal axis of the barrel from the first region to the second region. The barrier prohibits the expander member from moving from the second region to the first region.

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/439,500 filed Feb. 27, 2009 now U.S. Pat. No. 8,167,619 which is anational state application of Patent Cooperation Treaty Application No.PCT/IB2007/002396 filed Jan. 29, 2007, which claims priority to IsraeliPatent Application No. 177848 filed Sep. 3, 2006 each of which is herebyincorporated in its entirety.

FIELD OF THE INVENTION

The present invention pertains to expandable dental implants of highsurface area and to methods of in situ expanding the same.

BACKGROUND OF THE INVENTION

Endosseous root form implants-hereinafter referred to as “implants”—arewell known devices, which are adapted to support and receive dentalprosthetic pieces. Root form implants are generally cylindrical, with asurface area designed to promote good attachment to the jawbone. Mostimplants are made of titanium or of a titanium alloy, due to thebiocompatibility and high rate of osseointegration, i.e. thephysiological process of fusing with a living bone, of such a material.

Non-expandable implants have a continuous, cylindrically shaped body,which is threadedly fitted or press-fitted in a bore drilled within ajawbone. The prosthetic piece may not be received in the implant for aperiod of approximately five months, until bone tissue of the jawbonegrows and eventually fuses with the implant, causing discomfiture to apatient and necessitating several visits to an oral surgeon. During thisperiod, bone resorption is noticeable, due to the lack of pressurenormally applied by the extracted tooth onto the bone tissue. At times,the bore is improperly drilled, and is much larger than the fixeddiameter of the implant. As a result, the implant will not be properlysecured to the jawbone. Micro-movement of the implant relative to thewall of the bore is another cause of implant looseness.

The use of an expandable implant, whereby the outer diameter of theimplant relative to the wall of the bore is adjustable, obviates theaforementioned disadvantages of non-expandable implants. By providing acontrolled amount of lateral expansion, the outer surface of the implantis in pressured, frictional engagement with the jawbone. The degree offrictional engagement with the jawbone is increased by the shape of anexpanded implant, which is similar to that of the root of a tooth.Therefore the implant may receive a corresponding prosthetic piece andprovide sufficient functional loading for mastication immediately afterexpansion of the implant, due to the securing of the implant to thejawbone. When a prosthetic piece is attached to the implant immediatelyfollowing a tooth extraction, bone tissue growth, and consequentlyosseointegration, is induced by blood flow in the jawbone, the rate ofwhich is substantially equal to the blood flow rate prior to toothextraction. A substantially unchanging blood flow rate in the jawboneincreases the rate of implant osseointegration with the jawbone.Exemplary expandable implants are disclosed in U.S. Pat. Nos. 3,708,883,5,004,421, 5,470,230, 5,489,210, 5,931,674, 5,951,288 and 6,506,051.

The lateral expansion of the prior art implants is effected by a tubularenvelope having deformable elements at the apical end thereof and by anexpander member, generally of a frusto-conical shape, in engagement withsaid deformable elements. As the expander member is displaced along thelongitudinal axis of the tubular member, the expander member forces thedeformable elements to expand outwardly against the interior sidewall ofthe jawbone hole.

The securing means, by which the expander member of the prior artexpandable implants is secured to the tubular member, is formedlongitudinally above the expander. That is to say, the length of animplant is increased due to the arrangement of the securing meansrelative to the expander member. A short implant is of particularimportance for those patients having thin-walled or deformed jawbones,e.g. due to osteoporosis or bone resorption, since a bore drilled in thejawbone in order to receive a normally sized implant of the prior art isliable to injure the mandibular nerve or penetrate the sinus lining.Approximately 20-30% of those patients who require dental implants havethin-walled or deformed jawbones, and therefore these patients areprecluded from receiving prior art dental implants.

Prior art dental implants generally have a tubular barrel, which isscrewed into a bore formed in a jawbone, having a plurality of radialslits formed at the end which enters furthest into the bore and threadsformed on its interior surface. An expander screw has a frusto-conicallyshaped end surface and a cylindrical outer surface positioned betweencoronal threads and the end surface. The expander screw is shaped toengage and mate with the threads formed on the interior surface of thebarrel, such that advancement of the expander screw along the barreltoward the insertion end causes an end surface of the expander screw tocollide with the interior surface of the barrel and to expand theinsertion end outward into the surrounding bone. The slits reduce theavailable barrel surface area that engages the sidewall of the bore, andalso weaken the structure of the implant. Due to the reduced structuralstrength of the implant, each leg of the barrel formed between adjacentradial slits may twist and sever upon removal of the implant, if implantremoval is deemed necessary.

Furthermore, the exterior surface of the barrel, which is notimmobilized, is liable to be loosened from the sidewall of the jawbonebore over the course of time. Since the expander screw mates with thethreading formed on the interior surface of the barrel, reverse rotationof the expander screw, i.e. in a rotational direction opposite to thatwhich causes the barrel to press into the sidewall of the jawbone, dueto inter jaw dynamic compressive forces and fluctuating stresses,results in a loosening of the implant.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may beimplemented in practice, a plurality of preferred embodiments will nowbe described, by way of non-limiting example only, with reference to theaccompanying drawings, in which

FIG. 1 schematically presents a perspective view of a dental implant,according to one embodiment of the invention;

FIG. 2 is a perspective view of the dental implant of FIG. 1, with theexpander member removed;

FIG. 3A is a perspective view of an expanded dental implant of FIG. 1,with the outer body partially removed;

FIG. 3B is a perspective view of an expanded dental implant of FIG. 1;

FIG. 4 is a longitudinal cross-sectional view of the implant of FIG. 1,illustrating the expansion of an outer body;

FIG. 5 is a longitudinal cross-sectional view of the implant of FIG. 1,illustrating the immobilization of an expander member;

FIG. 6 a is a longitudinal cross-sectional views of a dental implant,according to another embodiment of the invention, showing a first stageof apical displacement of an expander member.

FIG. 6 b is a longitudinal cross-sectional views of a dental implant,according to another embodiment of the invention, showing a second stageof apical displacement of an expander member.

FIG. 6 c is a longitudinal cross-sectional views of a dental implant,according to another embodiment of the invention, showing a third stageof apical displacement of an expander member.

FIG. 7 a is a longitudinal cross-sectional views of a dental implant,according to yet another embodiment of the invention, showing a firststage of longitudinal displacement of an expander member.

FIG. 7 b is a longitudinal cross-sectional views of a dental implant,according to yet another embodiment of the invention, showing a secondstage of longitudinal displacement of an expander member.

FIG. 7 c is a longitudinal cross-sectional views of a dental implant,according to yet another embodiment of the invention, showing a thirdstage of longitudinal displacement of an expander member.

FIG. 8 is a perspective view of a dental implant, according to anotherembodiment of the invention, shown with the expander member removed;

FIG. 9 a is a bottom views of the dental implant of FIG. 8, during afirst stage of expansion.

FIG. 9 b is a bottom views of the dental implant of FIG. 8, during asecond stage of expansion.

FIG. 9 c is a bottom views of the dental implant of FIG. 8, during athird stage of expansion.

FIG. 10 a is a bottom views of a dental implant having indentationsformed in the inner surface of the outer body, during a first stage ofexpansion.

FIG. 10 b is a bottom views of a dental implant having indentationsformed in the inner surface of the outer body, during a second stage ofexpansion.

FIG. 10 c is a bottom views of a dental implant having indentationsformed in the inner surface of the outer body, during a third stage ofexpansion.

FIG. 11 is a perspective view of an expanded dental implant of FIG. 8;

FIG. 12 is a perspective view of the dental implant of FIG. 8 with theouter body partially removed, showing a longitudinal displacing means;

FIG. 13 is a longitudinal cross-sectional view of the implant of FIG. 1,illustrating the advantageously short longitudinal length of theimplant;

FIG. 14 is a perspective view of the implant of FIG. 8, showing meansfor restraining the rotation of an expander member.

FIG. 15 is a perspective view of the implant of FIG. 8, showing meansfor restraining the rotation of an expander member.

FIG. 16 is a lateral cross section of the implant's envelope in theapical area showing various possibilities of slit format; and,

FIG. 17A is a longitudinal cross sections of the implant's envelope,containing integral step and the expander inside its barrel.

FIG. 17B is a longitudinal cross sections of the implant's envelope,containing integral step and the expander inside its barrel.

FIG. 18 is a cross sectional view of an insert.

FIG. 19 is a perspective cross sectional view of the insert of FIG. 18.

SUMMARY OF THE INVENTION

In one embodiment a dental implant system for placement within a jaw ofa patient, includes an envelope and a movable expander. The envelopeincludes an outer surface and an inner surface defining a barrel. Atleast one barrier is located in the barrel. The barrel includes a firstregion on one side of the barrier and a second region on an opposingside of the barrier. The expander member is movable within the barrelalong a longitudinal axis of the barrel from the first region to thesecond region. The barrier prohibits the expander member from movingfrom the second region to the first region.

In another embodiment a dental implant for placement within a jaw of apatient includes an envelope having a barrel extending therethrough. Theenvelope has a radially expandable portion movable from a contractedconfiguration to an expanded configuration. The radially expandableportion includes at least one wall element defining an indentation inthe expandable portion. The wall element has a folded portion in thecontracted configuration and unfolds as the radially expanded portionmoves from the contracted configuration to the expanded configuration.

In still another embodiment a dental implant for placement within a jawof a patient includes an envelope having a barrel extendingtherethrough. The envelope has a radially expandable portion movablefrom a contracted configuration to an expanded configuration. Theradially expandable portion includes at least one slit having a lid atleast partially located therein. The lid extends from a longitudinaledge of the radially expandable portion and covers at least a portion ofthe slit as the radially expandable portion moves from the contractedconfiguration to an expanded configuration.

In still another embodiment a method for securing a dental implant in ajaw of a patient includes providing an elongated envelope having abarrel defining a longitudinal axis extending therethrough. The barrelhas a first region with a first diameter and a second region with asecond diameter less than the first diameter, the barrel includes atleast one step with a ledge portion extending away from the longitudinalaxis. An expander member is movable within the barrel.

A portion of the envelope is expanded from a contracted position to anexpanded position by moving the expander member within the barrel alongthe longitudinal axis from the first region to the second region. Aportion of the expander is secured with the barrier thereby prohibitingthe expander from moving from the second region toward the first region.

In a further embodiment, a method 23 for securing a dental implant in ajaw of a patient includes providing an elongated envelope having abarrel defining a longitudinal axis extending therethrough. The barrelhas a first region with a first diameter and a second region with asecond diameter less than the first diameter. The barrel includes atleast one step having a ledge portion that extends away from thelongitudinal axis. An expander member is movable within the barrel thatexpands a portion of the envelope from a contracted position to anexpanded position by moving the expander member within the barrel alongthe longitudinal axis from the first region to the second region. Aportion of the expander is secured by the barrier prohibiting theexpander from moving from the second region toward the first region.

It is hence one object of the present invention to disclose aself-contained expandable implant (100), comprising: (a) a threadlesselongated envelope (1) spanning along a main longitudinal axis (H);transformable from an initial contracted configuration to an expandedconfiguration; (b) at least one threadless conical expander (20)longitudinally displaceable within the envelope (1) from a coronalposition to an apical position or vice versa; such that the expander isthrusted by a pusher along the main longitudinal axis, the expander istightly fitted into the envelope in a singular predetermined position;wherein the expander is forcefully yet not rotatably immobilized by alock mechanism integrally incorporated within the envelope; and furtherwherein the combination of the envelope (1) module and the expander (20)modules is sufficient to secure the implant (100) in the expandedconfiguration. This implant may be especially adapted for short implantspreferably of about 5 to 16 mm. The fact that the immobilizing mechanismis one with the implant's envelope and lies within the radial horizontalplane of the envelope, allows further to develop short implants asdetailed above. Thus, this short implant may further especially beadapted to be implanted in thin-walled or deformed jawbones. Theexpandable implant (100) has a coronal portion attachable to aprosthetic piece.

It is a second object of the present invention to disclose an expandableimplant (100) adapted to maximize the surface area between the implantand the jawbone of a patient, comprising: (a) an elongated envelope (1)that spans along a main longitudinal axis; transformable from an initialcontracted configuration having S₀ (S is the external surface area ofthe implant) to an expanded configuration S₁, (b) threadless innerbarrel, its coronal diameter is greater than its apical diameter; (c) atleast one step (P) located in said envelope's (1) barrel; said step ischaracterized by side (L); depth (T_(Y)) wherein 0.01 mm<T_(Y)>1 mm, andangle (θ) wherein 25 degrees<θ>150 degrees, defining slope of side (L)wherein 0.05 mm<L>3 mm; said envelope comprising at least one slit (4),exceeding along said main longitudinal axis from said implant's apicalend; and (e) at least one lid (5), at least partially covering the slit(4) in the expanded configuration; and (f) at least one conical expander(20) having coronal diameter (20D_(C)) and apical diameter (20D_(A)), soas 20D_(C)≧20D_(A) or so as 20DA≧20D_(C); the expander (20) isvertically displaceable within the envelope (1) from a first coronalposition to a second apical position; the step is located between thecoronal to the apical locations; within the coronal position, theexpander (20) is supported on the at least one step (P), and the apicaldiameter of the implant (100) is S₀; the expander (20) may be thrustedapically by a pusher along the main longitudinal axis, it is forcefullyimmobilized within the apical location by the step, while increasing theapical diameter of the implant (100) to a predetermined S1; wherein theouter surface area of the implant (100) in the expanded configuration islarger than its outer surface area in the contracted configuration andthe implant is tightly fitted into the jawbone.

Within the scope of the present invention is an implant (100) having arounded cross section, or a polygonal cross-section. The expandableimplant therein having a main longitudinal axis H, wherein the length ofH is from about 5 mm<H>16 mm. The expandable implant has an initialsurface area S₀, wherein the difference (ΔS) between the initial surfaceS₀ and the expanded surface S1 is 8%≦Δ S≧30% and especially 8 to 25%.The implant's envelope (1) has an internal diameter wherein 3.2<d>7 mm.The implant's envelope comprises of N slits, N is an integer numberequal or higher one, especially 2<N>6. The expandable implant, whereinthe cross section of the slit is smooth, is lacerated or concave. Theexpandable implant, wherein the lid is at least partially integratedwithin the envelope. In a preferred embodiment of the invention the lidmay be also physically connected, glued, welded, punched, screwed,nailed or mechanically connected to the envelope. It may, at leastpartially, be constructed of metal alloys: especially non-alloy titaniumand titanium-based alloys, stainless steel, composite materials,polymers, or any combination thereof. The cross section of the lid maybe selected from a group including omega-shaped, w-shaped, v-shaped,accordion-shaped, wave-shaped or any combination thereof. The lateralfaces of the lid may be continuous or alternatively at least a portionof the lateral face of the cover is not continuous, e.g., comprising aplurality of apertures. The lid (5 a) may be at least partiallyconnected to the side wall of the envelope (1), moving freely in and outof a recess 7, in the facing wall of the envelope. The expandableimplant may be comprised at least partially of non alloys, metal alloys,especially non-alloys titanium, titanium-based alloys, stainless steel,composite materials, polymers or any combination thereof.

It is in the scope of the present invention implant to teach that theexpander (20) is displaced along the main longitudinal axis of envelope(1) in a vertical manner. It is further in the scope of the presentinvention implant to teach that the expander (20) expands the apicalportion of the envelope (1). During the implant's expansion the slits(4) are at least partially uncovered by the lids (5). The slits (4) maybe at least partially uncovered by the lids (5) in a discrete manner.The exposure of covered parts of the slits may expand the envelope'ssurface area into the expanded surface S₁.

A third object of the present invention is to teach an expandableimplant (100). Implant 100 comprises (a) an elongated envelope (1) spansalong a main longitudinal axis; being transformable from an initialcontracted configuration having D₀ (D is cross section diameter) to anexpanded configuration D₁ so as D₁>D₀; the envelope comprises threadlessinner barrel, the coronal diameter is greater than the apical diameterof the barrel; at least one step (P) located in the envelope's (1)barrel; the step is characterized by side (L) wherein 0.05 mm<L>3 mm;depth (T_(Y)) wherein 0.01 mm<Ty>1 mm, and angle (θ) wherein 25degrees<θ>150 degrees, defining slope of side (L); at least one conicalexpander (20) having coronal diameter (20D_(C)) wherein 1 mm<D_(C)>6 mmand apical diameter (20D_(A)) wherein 1 mm<D_(A)>6 mm, so as20D_(C)>20D_(A) or 20D_(A)>20D_(C); the expander (20) is verticallydisplaceable within the envelope (1) from a first coronal position to asecond apical position or vice versa; the step is located between thecoronal to the apical locations; wherein within the coronal position,the expander (20) is supported on at least one step (P), and the apicaldiameter of the implant (100) is D₀; and further wherein the expander(20) is thrusted apically by a pusher along the main longitudinal axis,it is forcefully immobilized within the apical location by the step,while increasing the apical diameter of the implant (100) to apredetermined D₁.

It is in the scope of the present invention to disclose that the step(P) may protrude radially into the threadless barrel may also andcontinuously or discontinuously extended therein.

It is in the scope of the present invention to disclose that the innerbarrel of the envelope may contain a plurality of N steps, where N is aninteger number equal or higher than 1, especially N equals 2.

It is in the scope of the present invention to disclose that theexpander may have a cylindrical, a polygonal or preferably a conicalcross section

It is in the scope of the present invention to disclose that theexpander is compressibly displaced along the main longitudinal axis in avertical manner, a rotating manner, helical manner or any combinationthereof. It is also in the scope of the invention to relate that theexpander (20) at least partially comprises compositions selected from agroup including metal alloys, especially titanium-based alloys andtitanium non alloys, stainless steel, other composite materials, or anycombination thereof. The expander may be at least partially rigid.

It is a fourth object of the present invention to disclose an expandableimplant (100) adapted to have an extended apical base, comprising athreadless inner barrel, its coronal diameter is greater than its apicaldiameter; at least one step (P) located in the envelope's (1) barrel;the step is characterized by side (L) wherein 0.05 mm<L>3 mm; depth(T_(Y)) wherein 0.01 mm<Ty>1 mm, and angle (θ) wherein 25 degrees<θ>150degrees, defining slope of side (L); at least one conical expander (20)having coronal diameter (20D_(C)) wherein 1 mm<D_(C)≧6 mm and apicaldiameter (20D_(A)) wherein 1 mm<D_(A)>6 mm, so as 20D_(C)≧20D_(A) or20D_(A)≧20D_(C); the expander (20) is vertically displaceable within theenvelope (1) from a first coronal position to a second apical positionor vice versa; the step is located between the coronal to the apicallocations; wherein within the coronal position, the expander (20) issupported on the at least one step (P), and the apical diameter of theimplant (100) is D₀; and further wherein the expander (20) is lungedapically by a pusher along the main longitudinal axis, it is forcefullyimmobilized within the apical location by the step, while increasing theapical diameter of the implant (100) to a predetermined D₁. It is in thescope of the present invention to disclose that the expander (20) may beirreversibly plugged within most apical position, and a continuousextended apical base is obtained. It is also in the scope of the presentinvention to disclose that the extended apical base may be flat. It isalso in the scope of the present invention to disclose that the expander(20) is adapted to be displaced apically in a discrete manner over twoor more steps.

It is a fifth object of the present invention to disclose a method forsecuring an expandable implant within a jawbone that comprises;obtaining a self-contained expandable implant (100) with (i) threadlesselongated envelope (1) spanning along a main longitudinal axis (H),transformable from an initial contracted configuration to an expandedconfiguration; and, (ii) at least one threadless conical expander (20)displacing longitudinally within the envelope (1) from a first coronalposition to a second apical position or vice versa; such that thethrusting of expander apically by a pusher along the main longitudinalaxis tightly fits the expander into the envelope in a singularpredetermined position; wherein immobilizing the expander is forcefully,yet not rotatably, by a lock mechanism integrally incorporated withinthe envelope and further wherein the combination of the envelope (1)module and the expander (20) modules is sufficient to secure the implant(100) in the expanded configuration. Adapting the implant especially forshort implants preferably of about 5 to 16 mm. Further adapting theimplant to be implanted in thin-walled or deformed jawbones. The factthat the immobilizing mechanism is one with the implant's envelope andlies within the radial horizontal plane of the envelope, allows furtherto develop short implants as detailed above. The expandable implant(100) having a coronal portion attachable to a prosthetic piece.

It is a sixth object of the present invention to disclose a method forexpanding the envelope of the implant, comprising; an expandable implant(100), having (a) an elongated envelope (1) spans along a mainlongitudinal axis; being transformable from an initial contractedconfiguration having S₀ (S is external surface area) to an expandedconfiguration S₁ so as S1>S0; the envelope comprising (i) threadlessinner barrel, its coronal diameter is greater than its apical diameter;(ii) at least one step (P) located in the envelope's (1) barrel; thestep is characterized by side (L); depth T_(Y) and angle (θ), definingslope of side (L); (iii) at least one slit (4), exceeding along the mainlongitudinal axis from the envelope's apical end; and, (iv) at least onelid (5), at least partially covering the slit (4) in the expandedconfiguration; and, (b) at least one conical expander (20) havingcoronal diameter (20D_(C)) and apical diameter (20D_(A)), so as20D_(C)≧20D_(A); or so as 20D_(A)≧20D_(C); the expander (20) isvertically displaceable within the envelope (1) from a first coronalposition to a second apical position or vice versa; the step is locatedbetween the coronal to the apical locations; wherein within the coronalposition, the expander (20) is supported on the at least one step (P),and the apical diameter of the implant (100) remains S₀; and furtherwherein the expander (20) is thrusted apically by a pusher along themain longitudinal axis, it is forcefully immobilized within the apicallocation by the step, while increasing the apical diameter of theimplant (100) to a predetermined S₁; (a) pushing the expander at leastonce by a pusher towards the apical end and displacing the same from thecoronal position to the apical position over at least one step; andhence, (b) increasing the apical diameter of the implant (100) and to apredetermined D₁, and thus immobilizing the expander in its final apicalposition; wherein the outer surface area of the implant (100) in theexpanded configuration is larger than its outer surface area in thecontracted configuration. The expander (20) may be compressiblydisplaced along the main longitudinal axis in a vertical manner.Expander (20) is expanding the apical portion of the envelope (1)wherein the lids (5) may be at least partially uncovering the slits (4)in a discrete or in a non discrete manner. The present method furtherdiscloses that the exposure of covered parts of the slits expand theenvelope's surface area into S₁.

It is a seventh object of the present invention to disclose a method forimmobilizing an expander within an implant's envelope, comprising; anexpandable implant (100), that has (a) an elongated envelope (1) thatspans along a main longitudinal axis; being transformable from aninitial contracted configuration having D₀ (D is cross section diameter)to an expanded configuration D₁ so as D₁>D₀; the envelope comprising (i)threadless inner barrel, diameter of the coronal portion is greater thanthe diameter of the apical portion; (ii) at least one step (P) locatedin the envelope's (1) barrel; the step is characterized by side (L);depth T_(Y) and angle (θ), defining slope of side (L); (iii) at leastone slit (4), exceeding along the main longitudinal axis from theenvelope's apical end; and, (b) at least one conical expander (20)having coronal diameter (20D_(C)) and apical diameter (20D_(A)), so as20D_(C)≧20D_(A); or as 20D_(A)≧20D_(C); the expander (20) is verticallydisplaceable within the envelope (1) from a first coronal position to asecond apical position or vice versa; the step is located between thecoronal to the apical locations; wherein within the coronal position,the expander (20) is supported on the at least one step (P), and theapical diameter of the implant (100) remains D₀; and further wherein theexpander (20) is thrustedable apically by a pusher along the mainlongitudinal axis; pushing the expander at least once by a pushertowards the apical end and displacing the same from the coronal positionto the apical position or vice versa, over at least one step; and hence,immobilizing the expander in its final apical position while increasingthe apical diameter of the implant (100) to a predetermined D₁. Themethod further discloses a step or steps of slightly, reversibly andinstantaneously expanding the envelope to a predetermined D₂, so asD₂>D₁, while irreversibly expanding the same from D₀ to D₁. The methodfurther discloses a step or steps of displacing the expander along themain longitudinal axis in a vertical manner, a rotating manner, helicalmanner or any combination thereof.

It is an eighth object of the present invention to disclose a method ofproviding a dental implant with an extended apical base comprises anexpandable implant (100) with (a) an elongated envelope (1) that spansalong a main longitudinal axis; transformable from an initial contractedconfiguration having D₀ (D is cross section diameter) to an expandedconfiguration D₁ so as D₁>D₀; the envelope comprising (i) threadlessinner barrel its coronal diameter is greater than its apical diameter;(ii) at least one step (P) located in the envelope's (1) barrel; thestep is characterized by side (L); depth (T_(Y)) and angle (θ), definingslope of side (L); (iii) at least one slit (4), exceeding along the mainlongitudinal axis from the envelope's apical end; and, (b) at least oneconical expander (20) having coronal diameter (20130 and apical diameter(20D_(A)), so as 20D_(C)≧20D_(A) or so as 20D_(A)≧20D_(C); the expander(20) is vertically displaceable within the envelope (1) from a firstcoronal position to a second apical position; the step is locatedbetween the coronal to the apical locations; the expander (20) isvertically displaceable inside the envelope (1) from a coronal positionto an apical position; the step is located between the coronal to theapical locations; within the coronal position, the expander (20) issupported on the at least one step (P), and the apical diameter of theimplant (100) is D₀.

The method further teaches thrusting the expander (20) towards theapical end by means of a pusher along the main longitudinal axis, thus,forcefully immobilizing the expander (20) within the apical location bythe step (P), increasing the apical diameter of the implant (100) to apredetermined D1; and, irreversibly plugging the expander (20) within amost apical position, so as an extended apical base is obtained. Themethod further discloses that the obtained extended apical base may beflat. The method further discloses step or steps of displacing theexpander (20) apically in a discrete manner over two or more steps (P).

It is a ninth object of the present invention to disclose a method foranchoring a dental implant within a bore drilled in the jawbone of apatient; comprising a self-contained expandable implant (100), having:(a) threadless elongated envelope (1) spanning along a main longitudinalaxis (H); the elongated envelope (1) is transformable from an initialcontracted configuration having S₀ (S is the external surface area ofthe implant) to an expanded configuration S₁; the elongated envelope istransformable from an initial contracted configuration having D₀ (D iscross section diameter) to an expanded configuration D₁ so as D₁>D₀; theenvelope also comprising; the envelope comprising: (i) at least one slit(4), exceeding along the main longitudinal axis from the envelope'sapical end; (ii) at least one lid (5), at least partially covering theslit (4) in the expanded configuration; (iii) threadless inner barrel,the depth of barrel wall in its apical portions is greater than itscoronal portions; and, (iv) at least one step (P) located in theenvelope's (1) barrel; the step is characterized by side (L); depth(T_(Y)) and angle (A), defining slope of side (L); (b) at least onethreadless conical expander (20) longitudinally displaceable within theenvelope (1) from a first coronal position to a second apical positionor vice versa; such that the expander is thrusted apically by a pusheralong the main longitudinal axis, the expander is tightly fitted intothe envelope in a singular predetermined position; the conical expander(20) having coronal diameter (20D_(C)) and apical diameter (20D_(A)), soas 20D_(C)≧20D_(A) or so as 20D_(A)≧20D_(C); the step is located betweenthe coronal to the apical locations; wherein within the coronalposition, the expander (20) is supported on the at least one step (P),and the apical diameter of the implant (100) remains D₀; and furtherwherein the expander (20) is forcefully immobilized within the apicallocation by the step, while increasing the apical diameter of theimplant (100) to a predetermined D₁ and to a predetermined S₁; whereinthe expander is forcefully, yet not rotatably, immobilized by a lockmechanism, especially a step, integrally incorporated within theenvelope; further wherein the envelope (1) and the expander (20) aresolely required to secure the implant (100) in the expandedconfiguration; further wherein the expandable implant (100) is adaptedespecially to maximize the surface area between the implant and thejawbone; and further wherein the expandable implant (100) having anextended apical base when the expander (20) irreversibly plugs into themost apical position.

It is another object of the present invention to disclose a method forsecuring an expandable implant within a jawbone and for immobilizing anexpander within an implant's envelope comprising; (a) obtaining animplant with (I) threadless elongated envelope (1) spanning along a mainlongitudinal axis (H); the elongated envelope (1) is transformable froman initial contracted configuration having S₀ (S is the external surfacearea of the implant) to an expanded configuration S₁; the elongatedenvelope is transformable from an initial contracted configurationhaving D0 (D is cross section diameter) to an expanded configuration D1so as D₁>D₀; the envelope also comprising; the envelope comprising: (i)at least one slit (4), exceeding along the main longitudinal axis fromthe envelope's apical end; (ii) at least one lid (5), at least partiallycovering the slit (4) in the expanded configuration; (iii) threadlessinner barrel, the depth of barrel wall in apical portions is greaterthan in coronal portions; and, (iv) at least one step (P) located in theenvelope's (1) barrel; the step is characterized by side (L); depth(T_(Y)) and angle (A), defining slope of side (L); and, (II) at leastone threadless conical expander (20) longitudinally displaceable withinthe envelope (1) from a first coronal position to a second apicalposition or vice versa; such that the expander is thrusted apically by apusher along the main longitudinal axis, the expander is tightly fittedinto the envelope in a singular predetermined position; the conicalexpander (20) having coronal diameter (20D_(C)) and apical diameter(20D_(A)), so as 20D_(C)≧20D_(A) or so as 20D_(A)≧20D_(C); the step islocated between the coronal and the apical locations; wherein in thecoronal position, the expander (20) is supported on the at least onestep (P), and the apical diameter of the implant (100) remains D₀; (a)pushing the expander at least once by a pusher towards the apical endand displacing longitudinally the same within the envelope (1) from thefirst coronal position to the second apical position over at least onestep; tightly fitting the expander into the envelope in a singularpredetermined position; (b) increasing the apical diameter of theimplant (100) and to a predetermined D₁, and thus immobilizing theexpander in its final apical position; wherein the outer surface area ofthe implant (100) in the expanded configuration is larger than its outersurface area in the contracted configuration; and, (c) forcefullyimmobilizing the expander in its final apical position by the step (P)while increasing the apical diameter of the implant (100) to apredetermined D₁, wherein immobilizing the expander is achievedforcefully, yet not rotatably, by a lock mechanism integrallyincorporated within the envelope. The method further discloses providinga dental implant with an extended apical base also comprisingirreversibly plugging the expander (20) into the most apical position,so as an extended apical base is obtained.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is provided, alongside all chapters of thepresent invention, so as to enable any person skilled in the art to makeuse of the invention and sets forth the best modes contemplated by theinventor of carrying out this invention. Various modifications, however,will remain apparent to those skilled in the art, since the genericprinciples of the present invention have been defined specifically toprovide expandable dental implants of high surface area and to methodsof expanding and anchoring the same in situ.

The term “longitudinal” refers hereinafter to the direction of the longaxis or “top-to-bottom” axis.

The term “apical” refers hereinafter to the direction of the dental rootor oral cavity.

The term “coronal” refers hereinafter to the direction of the crown ofthe tooth.

The term “expandable” refers hereinafter to the capability of theimplant to increase its lateral dimension.

The term “expander” refers hereinafter to an element that causesexpansion, particularly by pressing on the inner surface of an outerbody.

The term “immobilized expander” refers hereinafter is an expander thatcan no longer be longitudinally or laterally displaced.

The term “slit” refers hereinafter to an aperture in the envelope of theimplant that can be opened or closed.

The term “lid” refers hereinafter to a part of the envelope coveringsaid slit.

The term “outwards” refers hereinafter to the movement in the directionof the wall of the bore in the jawbone.

The term “inwards” refers hereinafter to the movement in the directionof the longitudinal axis of the implant.

The term “S₀” refers hereinafter to the total surface area of theenvelope in its initial contracted condition when the slits are coveredby the lids.

The term “S₁” refers hereinafter to the total surface area of theenvelope in its secondary fully expanded condition when the slits aremaximally uncovered by the lids.

The term “D₀” refers hereinafter to the external diameter of theenvelope in its initial contracted condition; wherein d is the internaldiameter of the same.

The term “D₁” refers hereinafter to the diameter of the envelope in itssecondary fully expanded condition.

The term “contracted configuration” refers hereinafter to the initialclosed/shrunk configuration of the implant.

The term “expanded configuration” refers hereinafter to the secondaryenlarged, opened configuration of the implant.

The term “lock mechanism” refers hereinafter to the state of theexpander inside the envelope where it is positioned and trapped by astep.

The term “pusher” refers hereinafter to the external mean provided toforce the expander to displace inside the inner barrel of the envelope.

The term “step” refers hereafter to a recess or protruding barrier whicha lock mechanism may latch onto.

The term “about” refers hereafter to ±20% of the defined measure.

The present invention, according to one of its embodiments, depicts anexpandable dental implant used to achieve maximal contact area andoptimal anchoring of the implant inside the jawbone.

The implant is assembled of essentially two components; an elongatedenvelope that spans along a main longitudinal axis; transformable froman initial contracted configuration having a limited minimal externalsurface area to an expanded configuration where the envelope's totalsurface area is greater. The implant's envelope has at least one slit,exceeding along the implant's main longitudinal axis starting from theapical end; and at least one lid which at least partially covers theslit in the expanded configuration. The surface area of the expandeddental implant is larger than the surface area in the initial contractedconfiguration. In a preferred embodiment of the invention the expandabledental implant has a rounded cross section. The expandable dentalimplant has a polygonal cross section according to another preferredembodiment of the invention. The expandable implant has a mainlongitudinal axis H, with a length of about 5 to 16 mm, an initial innerbarrel diameter, d, of about 3.2 to 7 mm according to one embodiment ofthe invention. The expandable implant in its expanded condition has anenlarged surface area S₁ wherein the difference (ΔS) between the initialS₀ and the expanded S₁ is 8%≦ΔS≧30% according to another embodiment ofthe invention.

The expandable implant has in its envelope N number of N slits, where Nis an integer number equal or higher to one, preferably but notnecessarily 2<N>6. When depicting a horizontal cross section of the slitit can be formed as smooth, lacerated or concave. The slits in theexpandable implant's envelope are exposed according to one embodiment ofthe invention. The slit in the expandable implant's envelope are atleast partially covered by a lid which is at least partially integratedwithin said envelope, in the form of folds or pleats, according toanother embodiment of the invention. The lid covering the slits isphysically connected, glued, welded, punched, screwed, nailed, ormechanically interconnected to the implant's envelope according toanother embodiment of the invention.

The lid partially covering the slit in the implant's envelope has across section selected from a group including omega-shaped, w-shaped,v-shaped, accordion-shaped, wave-shaped or any combination thereof.

The lid partially covering the slit in the implant's envelope has acontinuous lateral face according to one embodiment of the invention.The lid partially covering the slits in the implant's envelope has atleast a portion of the lateral face is not continuous, e.g., comprisinga plurality of apertures according to another embodiment of theinvention.

The lid partially covering the slit in the implant's envelope isimmobilized partially to one side of the slit, moving freely in and outof a recess 7, in the envelope's wall, according to another embodimentof the invention.

The expandable implant can be manufactured at least partially from metalalloys, especially titanium-based alloys; titanium based non alloys,stainless steel, composite materials, polymers or any combinationthereof.

The lid covering the slits is manufactured at least partially from metalalloys, especially titanium-based alloys, titanium non alloys, stainlesssteel, composite materials, polymers, or any combination thereofaccording to one embodiment of the invention. The lid covering the slitsis manufactured at least partially from flexible materials, especiallypolymers, composite materials, or any combination thereof according toanother embodiment of the invention.

The expandable implant depicted in the invention is expanded by twocomponents: the envelope 1, being transformable from an initialcontracted configuration having across section diameter of D₀, to anexpanded configuration where the diameter is D₁, so as D₁≧D₀.

The envelope 100, has a threadless inner barrel, the thickness of theenvelope's wall in its apical portion is greater than in its coronalportion. Located inside the envelope's inner barrel there is at leastone step P. Step P is characterized by side L, depth T_(Y), wherein Tyis between about 0.01 to 1 mm, and angle (θ) is between about 25 degreesto 150 degrees, defining slope of side (L) ranging from about 0.05 mm to3 mm. The expandable implant has at least one conical expander 20,located inside the inner barrel, having coronal diameter 20D_(C), where1 mm<20D_(C)>6 mm, and apical diameter 20D_(A), where 1 mm<20D_(A)>6 mm,so as 20D_(C)≧20DA according to one embodiment of the invention, or20D_(C)≧20D_(A) according to yet another embodiment of the invention.

According to another embodiment of the present invention, the expander20 is vertically displaceable within the envelope 1, from a firstcoronal position to a second apical position, or vice versa, by apusher. The step P is located between the coronal and the apicalpositions. When the expander 20, is in the initial coronal position itis supported on at least one step P, and the apical diameter of theimplant 100 is D₀. When the expander 20 is thrusted apically by thepusher along the main longitudinal axis, it is forcefully immobilized inthe apical location by the step. As the diameter of the expander islarger than the diameter of the inner barrel in the apical position,this displacement expands the implant by increasing its apical diameterto the predetermined expanded diameter D₁.

According to another embodiment of the present invention, the step Plocated inside the threadless inner barrel of the envelope protrudesradially from its wall according to one embodiment of the invention.According to another embodiment of the present invention, the step Plocated inside the threadless inner barrel of the envelope protrudesradially from its wall and continuously extended therein according toanother embodiment of the invention. The step P located inside thethreadless inner barrel of the envelope protrudes radially from its walland discontinuously extended therein according to another embodiment ofthe invention.

The inner barrel of the implant's envelope has a plurality of N steps, Nis an integer number equals to or higher than 2 according to oneembodiment of the invention. The inner barrel of the implant's envelopehas a plurality of N steps, where N equals 2 or according to anotherembodiment of the invention. The inner barrel of the implant's envelopehas a plurality of N steps, where N equal 3 according to anotherembodiment of the invention.

The expander located inside the barrel of the implant's envelope havinga cylindrical cross section according to one embodiment of theinvention. The expander located inside the barrel of the implant'senvelope having a polygonal cross section according to anotherembodiment of the invention. The expander located inside the barrel ofthe implant's envelope having a conical cross section according toanother embodiment of the invention.

According to another embodiment of the present invention, the expander20 is pushed to its secondary apical position and is permanentlyimmobilized by the steps inside the envelope's inner barrel. In thisprocess, while irreversibly expanding from D₀ to D₁, the implant'senvelope is adapted to slightly, reversibly and instantaneously expandradially to a predetermined diameter D₂, so as D₂>D₁. This slightexpanding to the D₂ diameter is reversed immediately to the D₁ diameterwhen the expander is located in its apical position under the step. Thusthe envelope further immobilizes the expander in this apical position.

According to another embodiment of the present invention, the expanderlocated inside the barrel of the implant is compressibly displaced alongthe main longitudinal axis in a vertical manner, a rotating manner,helical manner or any combination thereof.

According to another embodiment of the present invention, the expanderlocated inside the barrel of the implant's envelope at least partiallymanufactured from compositions selected from a group including metalalloys, especially titanium-based alloys, stainless steel, othercomposite materials, or any combination thereof.

According to another embodiment of the present invention, the expanderlocated inside the barrel of the implant's envelope is at leastpartially rigid.

The expandable implant in its final expanded position has an extendedcontinuous apical base further increasing the surface area to promotethe process of osseointegration and also to eliminate entry of infectioninto the implant's inner barrel.

The expander 20 located inside the inner barrel of the implant'senvelope 1 being in its initial coronal position is supported on atleast one step P, and the apical diameter of said implant 100 is D₀.When the expander is thrusted towards the apical end by a pusher it isforcefully immobilized within the apical location by the step, whileincreasing the apical diameter of said implant (100) to a predeterminedD₁. In this state the expander 20 irreversibly plugs within most apicalposition, an extended apical base is obtained.

According to another embodiment of the present invention, the expanderpositioned in the apical end of the implant creates an extended apicalflat base.

According to another embodiment of the present invention, the expanderpositioned in the apical end of the implant is adapted to be displacedapically in a discrete manner over two or more steps.

According to another embodiment of the present invention, the expander20 located in the initial coronal position is supported on at least onestep P, and the apical diameter of said implant 100 is S₀. When theexpander 20 is thrusted apically by a pusher along the main longitudinalaxis, it is forcefully immobilized within said apical location by saidstep, while increasing the apical diameter of the implant 100 to apredetermined S₁. In this expanded configuration the outer surface areaof the implant 100 is larger than its outer surface area in the initialcontracted configuration. According to another embodiment of the presentinvention, the process of the enlargement of the envelope's surface areais carried out by of the slits 4 located along the main axis in theapical portion of the implant's envelope 1. As the expander compressiblydisplaces along said main longitudinal axis to the apical position, thelids 5 are forced to open and uncover the slits, thus unfolding andenlarging the implant's surface area.

According to another embodiment of the present invention a method forimmobilizing an expander within an implant's envelope is provided. Themethod outlines obtaining an expandable implant 100, comprising (a) anelongated envelope 1 that spans from a coronal end to an apical endalong a main longitudinal axis; being transformable from an initialcontracted configuration having a cross section diameter D₀ to anexpanded configuration D₁ so as D₁>D₀. The implant's envelope comprises(i) a threadless inner barrel; the thickness of barrel wall in apicalportion is greater than the thickness in coronal portions (ii) at leastone step P located in the envelope's inner barrel. The step ischaracterized by side L, thickness T_(Y) and angle θ, defining slope ofside L (iii) at least one slit 4, exceeding along said main longitudinalaxis from said envelope's apical end; and, (b) at least one conicalexpander 20 having coronal diameter 20D_(C) and apical diameter 20D_(A),so as 20D_(C)≧20D_(A) or 20D_(A)≧20D_(C). The expander 20 is verticallydisplaceable within said envelope 1 from a first coronal position to asecond apical position, or vice versa, when the step P is locatedbetween the coronal and the apical locations. Within the initial coronalposition, the expander 20 is supported on at least one step P, and theapical diameter of the implant 100 remains D₀. The process of expandingthe implant and immobilizing the expander inside the envelope proceedsin a stepwise manner. The expander 20 is thrusted apically at least onceby a pusher along the main longitudinal axis over at least one step andhence immobilizing the expander under the step, in its final apicalposition while increasing the apical diameter of the implant to apredetermined D₁.

According to another embodiment of the invention, the methodadditionally comprises a step or steps of slightly, reversibly andinstantaneously expanding the envelope to a predetermined diameter D₂,so as D₂>D₁, while irreversibly expanding the same from D₀ to D₁. Thediameter D₂ is formed only when the expander moves exactly across theplanar axis of the step. Once moving across the step, the over expandeddiameter D₂ decreases to the predetermined expanded diameter D₁. Theprocess of momentarily reversible over-expanding and withdrawing back toD₁, further immobilizes the expander within the envelope in the apicalposition.

According to another embodiment of the invention, the methodadditionally comprises a step or steps of displacing said expander alongsaid main longitudinal axis in a vertical manner, a rotating manner,helical manner or any combination thereof.

According to another embodiment of the invention, the methodadditionally comprises obtaining an expandable dental implant having anextended apical base in its final expanded position, thus furtherincreasing the surface area to promote the process of osseointegrationand also to eliminate entry of infection into the implant's innerbarrel. The expander 20 is vertically displaced within the implant'senvelope 1, by thrusting said expander 20 towards the apical end bymeans of a pusher along the main longitudinal axis, from a first coronalposition to a second apical position. The expander is forcefullyimmobilized under the step P, thus increasing the apical diameter of theimplant to a predetermined D₁; and, irreversibly plugging the expander20 within a most apical position, so as an extended apical base isobtained.

According to another embodiment of the invention the expander 20 isdisplaced over the steps in a discrete manner over two or more steps.

The extended apical base is flat according to another embodiment of theinvention.

Reference is now made to FIG. 1 illustrating one preferred embodiment ofan expandable dental implant, generally designated as 100. Implant 100comprises outer envelope 1 and annular either conical expander member20, which is received in a threadless barrel of envelope 1, when thesmall diameter side of the expander is directed either towards the apexor towards the corona, and is in contact with envelope's wall 12thereof. The most coronal portion of the implant 15 is possibly yet notexclusively provided with external threading 17, which facilitatesimplanting within a bore drilled within a jawbone, or within a recessformed by the extraction of a tooth.

Both envelope 1 and expander 20 are possibly made from a high-strengthand biocompatible material, such as titanium or a titanium alloy.Preferably both the body and expander member are made from the samematerial, so as to prevent corrosion, which normally results from thegeneration of an electrochemical cell by the placement of two differentmetals in an aqueous environment, such as blood and saliva, due to thepotential difference between the two metals.

The basic format of a dental implant comprising only two components(namely envelope and expander) has a significant advantage overexpanding implants of the prior art. The elimination of additionalscrewing means to move the expander inside the envelope allows for thedevelopment of significantly shorter (about 6 to 10 mm) implants thatcan be used in special cases of thin-walled or deformed jawbonespatients.

A possible structure of envelope 1 is shown in a non-limiting manner inFIG. 2, without showing expander 20 being accommodated thereto.

A plurality of N narrow longitudinal slits 19 are formed in wall 12 ofenvelope 1, wherein N is an integer number equal or higher than one.Here e.g., four vertical slits are shown, defining thereby fourelastically deformable clasps 21 that are adapted to expand laterallyoutwards as an expander 20 is longitudinally displaced along the mainlongitudinal axis of eth implant towards the apical end.

The inner surface 14 of each clasp, at the apical end thereof, is formedwith N circumferential steps 25 (also denoted P), e.g., 3 steps. It isin the scope of the invention wherein the steps of each adjacent claspare coplanar, e.g. the most coronal step of each clasp is coplanar anddefines an arc of a circle which is perpendicular to, and whose centercoincides with, the longitudinal axis of envelope 1.

The coronal end of envelope 1 is possibly provided with head 29, havinge.g., a hexagonal shape as illustrated, or formed with any otherconvenient shape, preferably yet not exclusively with a smaller widththan the outer diameter of wall 12, and serves as an anti-rotationdevice for a prosthetic piece that is to be secured thereto by e.g., asimilarly shaped recessed socket formed in said prosthetic piece.

Inner surface 14 of each clasp 21 is also formed with a plurality of Ninclined backs 27, wherein each back is associated with a correspondingstep 25. The curvature of four corresponding backs 27 is preferably yetnot exclusively substantially equal, selected to be approximately equalto the curvature of the expander member. The inclination of each back issubstantially equal to that of the conical 1 expander, placed in eitherdirection, so as to allow for the expander to securely rest against eachset of N backs during lateral expansion.

Prior to the implantation of implant 10, expander 20 is press-fittedinto the apical end of unexpanded envelope 1, which has an innerdiameter substantially equal to that of the outer diameter of the apicalend of the expander, and therefore envelope 1 assumes according to oneembodiment a tubular shape, as illustrated in an out of scale scheme ofFIG. 1.

During coronal displacement of expander 20, as shown in FIGS. 3 a and 3b, side 22 of the expander bears against the back of a more coronalstep, if existing. Since the outer diameter of the expander is greaterthan the spacing between diametrically opposite backs of the morecoronal step, the apical backs are forced to move outwards, due to theflexibility of clasps 21.

FIG. 4 illustrates the outward expansion of clasps 21 during coronaldisplacement of expander member 20. Each clasp 21 is formed with acoronal step 25 a and coronal back 27 a, intermediate step 25 b andintermediate back 27 b, and apical back 27 c, with the inner diametergenerated by a coronal step 25 a being smaller than that generated byintermediate step 25 b. As expander member 20 is coronally displaced,clasps 21 are gradually urged apically outwards. For example, the outerdiameter of side 22 at contact point A is greater than the spacingbetween diametrically opposite apical backs 27 c, and consequently thethree apical backs are urged apically outwards until being flexed topositions 27 a′, 27 b′ and 27 c′, respectively. Greater coronaldisplacement of the expander member results in greater outward flexingof the clasps 21.

As expander member 20 is further coronally displaced, as shown in FIG.5, clasps 21 continue to outwardly expand, due a changing contact pointbetween side 22 and the apical backs 27 c. When apical end 31 of theexpander member is displaced to point C approximately coincident with,but slightly apical from, intermediate step 25 b, backs 27 a-c assumethe inclination shown by the solid lines relative to longitudinal axis Hof the implant. Following additional coronal displacement, apical end 31of the expander is displaced beyond the coronal end of backs 27 c topoint C′, and backs 27 a-c cease to contact the expander. Potentialenergy stored in the angularly deformed legs 21, which is impartedthereto by the displacing means, as will be described hereinafter, istherefore released when expander member 20 is separated from the innersurface of the legs. Backs 27 a-c accordingly tend to return to theiroriginal position, as shown in FIG. 4, but are retarded by the expander20. Backs 27 a-c are consequently inwardly displaced, as indicated bythe dashed line, following the release of potential energy from each leg21, until back 27 b abuts side 22 of the expander at contact point B′and step 25 b abuts the expander member at contact point C′. The backsthen assume an inclination relative to axis H, as represented by thedashed lines at 27 a′-c′.

Substantially radial forces applied to expander 20 by each leg atcorresponding contact points B′ and C′ prevent the expander member frombeing apically displaced. When the displacing means is detached from theexpander, the latter is also prevented from being longitudinallydisplaced. As a result, the expander is immobilized, and will not beloosened over the course of time. Conversely, a threaded expander ofprior art expandable implants is frictionally restrained by an outerbody, and may be rotated in reverse and loosened due to inter jawdynamic compressive forces or any movement causing vibrations likewalking, running or jumping (and fluctuating stresses). Threadedimmobilization of prior art implants is dependent solely on frictionalforces and coefficients that depend on the materials, surface areatexture and the implant's geometry.

It will be appreciated that expander 20 may not be apically displayedfrom back 27 b′ to back 27 c′ by a longitudinal force after beingimmobilized, since step 25 b′ supports apical end 31 of the expander,radially extending inwards from side 22. However, the expander may becoronally displaced from back 27 b′ to back 27 a′ by the displacingmeans since step 25 a′ is oblique to side 22, and therefore back 27 b′will be urged outwards by side 22 during coronal displacement of theexpander member.

As shown in FIGS. 6 a-c, the outer body is also expandable upon apicaldisplacement of the expander. Implant 100, as shown in FIG. 6 a beforeapical displacement of the expander, comprises envelope 1 andfrusto-conical expander 20, which is positioned such that its coronalend 32 has a larger diameter than its apical end 34. The inner surfaceof body 36 at its apical deformable end is formed with a deformableportion 37, which is inclined with respect to axis H of body 36, and anormally straight portion 38 before expansion of the outer body, whichis formed apically to inclined portion 37. As expander 20 is apicallydisplaced, as shown in FIG. 6 b, outer wall 22 of the expander applies aradial force to the inclined deformable portion 37. Since the apicaldimension of the spacing between opposed inclined portions 37 is lessthan the outer diameter of coronal end 32 of expander 20, portions 37are flexed in response to the apical displacement of the expander, andbody 36 expands. Following additional apical displacement of expander20, as shown in FIG. 6 c, coronal end 32 of the expander member isimmobilized by step 39, which is formed apically to inclined portion 37,and by straight portion 38.

FIGS. 7 a-c illustrate another preferred embodiment of the presentinvention, wherein the rigid expander 20 is cylindrical. Implant 100, asshown in FIG. 7 a before coronal displacement of the expander, comprisesouter tubular body 45 formed with a cylindrical recess 47, which issuitably sized so as to immobilize cylindrical expander 50. The innersurface of body 45 apical to recess 47 is formed with a deformableportion 48, which is inclined with respect to outer wall 51 of theexpander. As expander 50 is coronally displaced, as shown in FIG. 7 b,outer wall 51 of the expander applies a radial force to the inclineddeformable portion 48. Since the apical dimension of the spacing betweenopposed inclined portions 48 is less than that of expander 50, portions48 are flexed in response to the coronal displacement of the expandermember, and outer wall 42 of body 45 accordingly assumes a concave,parabolic shape, due to the apical expansion thereof. Followingadditional coronal displacement of expander 50, as shown in FIG. 7 c,apical end 53 of the expander is displaced into recess 47. Sincedeformable portion 48 does not encounter resistance by expander 50,portion 48 is inwardly displaced and wall 46 of recess 47 contacts outerwall 51 of the expander, thereby immobilizing the expander.

FIGS. 8-15 illustrate another preferred embodiment of the inventionwherein the outer body is continuous, not being formed with slits andlegs. With such a configuration, penetration of infection into thejawbone is prevented. Additionally, in the expanded position, a farlarger (by 10-15%) surface area is provided, compared to expandableimplants of prior art. Therefore, the process of osseointegration isfurther promoted. The outer body is deformable, and thereforeexpandable, due to a novel construction wherein a plurality ofthin-walled, curved indentations are formed in the wall of the outerbody.

As shown in FIG. 8, tubular outer body 65 is formed with a plurality ofequally spaced, longitudinally extending indentations 55. Eachindentation 55 is formed by a thin-walled element 57, which issignificantly thinner than the relatively thick wall 58 of the remainingportions of outer body 65. When outer body 65 is not expanded,indentations 55 are in a collapsed configuration, with each thin-walledelement being curved and facing inwards.

FIGS. 9 a-c illustrate the change in shape of an outer body formed witha plurality of indentations, during expansion thereof. When an outerbody is unexpanded, as indicated by radius R₁ in FIG. 9 a, thecircumferential length G of a thick-walled portion 58, e.g. one that isformed with steps and backs as described hereinabove, is significantlygreater than the circumferential length L of a thin-walled element 57.Upon longitudinal displacement of the expander member, the side of theexpander member outwardly presses on each rigid thick-walled portion 58,due to the greater outer diameter of the expander member relative tothat of the thick-walled portions. Consequently, thick-walled portions58 are outwardly displaced to radius R₂ as shown in FIG. 9 b. Eachthin-walled element 57 is outwardly flexed due to the outward force Fapplied to each thick-walled portion 58 by the expander member. Since athick-walled portion 58 is connected to an adjacent thin-walled element57, the outward displacement of a thick-walled portion applies a forceto the adjacent thin-walled element, causing the curve of eachthin-walled element to be flattened. Upon maximum longitudinaldisplacement of the expander, the thick-walled portions expand to aradius of R₃ as indicated in FIG. 9 c, and the thin-walled elements 57assume the general shape of thick-walled portions 58, with thecircumferential length G of a thick-walled portion being substantiallyequal to the circumferential length L of a thin-walled element.

In FIGS. 10 a-c, the inner surface of the outer body is formed with aplurality of curved indentations, with the concave side of thin-walledelements 60 facing inwards. Once again, the thick-walled portions 58 areshown to be progressively outwardly expanded, from a minimum radius ofR₁ to a maximum radius of R₃, until thin-walled elements 61 assume thegeneral shape of the thick-walled portions.

As shown in FIG. 11, body 65 is frusto-conical when expanded. Thelongitudinal displacement means may be a screw engaged by threading theformed internally to the expander member. Head 67 of the screw is alsoshown, and is supported during rotation by hexagonal head 29 attachableto a prosthetic piece.

In FIG. 12, screw 66 longitudinally extends from head 67 to expander 20,with which it may be threadably engaged, passing through head 29 andannular portion 69 of body 65. During rotation of head 67, e.g. with anAllen wrench, expander member 20 is longitudinally displaceable and body65 is expandable. After expander 20 is immobilized, screw 65 may beremoved therefrom and body 65 retains its expanded configuration.

Following removal of the screw from expander member 20, cavity 61internal to annular portion 69 is accessible, as shown in FIG. 13.Internal threading 59, which encircles cavity 61 and longitudinallyextends from head 29 to approximately the back of the most coronal step,e.g. with a gap of no more than 0.1 mm, is adapted for engagement with aprosthetic piece. It will therefore be appreciated that the body is ofthe smallest possible length, since expander 20 is not formed withexternal threading, and therefore the longitudinal dimension of theexpander is equal to the longitudinal dimension of side 22 whichcontacts a step 27. In contrast, prior art expandable implants arenormally formed with external threading for coupling with the innersurface of the outer body, extending from the coronal end 71 of thecontact element of the expander which bears against the inner surface ofdeformable legs, and thereby increasing the length of the expandermember and of the outer body.

The coefficient of friction between expander 20 and backs 27 is usuallysufficiently high so as to provide a reactive force when screw 66 (FIG.12) is rotated, in order to longitudinally displace the expander member.At times, however, due to the materials selected or due to themanufacturing tolerances, a sufficient rotational reactive force is notprovided, and other means must be employed to prevent rotation of theexpander member during longitudinal displacement.

FIGS. 14 and 15 illustrate an exemplary means of preventing rotation ofthe expander during longitudinal displacement. Side wall 74 of expandermember 75 is formed with a plurality of substantially equally spacedpointed radial projections 77, as shown in FIG. 14, or circumferentialprojections, as shown in FIG. 15. Each projection is rotationallyrestrained by a similarly shaped groove, e.g. a circumferential groove81 in FIG. 15, which is longitudinally formed in the inner surface ofbody 65. Upon rotation of screw 66, each projection is longitudinallydisplaced in a corresponding groove, while expander member 75 isprevented from being rotated.

The longitudinal displacing means may be a rod (not shown), or any otherconvenient arrangement, which couples with a suitable connecting deviceformed on the coronal end 71 (FIG. 13) of the expander device, as wellknown to those skilled in the art. The displacement means may beinserted within cavity 61. As the displacing means is coronally pulled,expander 20 is similarly coronally displaced and body 65 expands.

FIG. 16 illustrates a lateral cross section of the apical portion of theimplant's envelope 1; envelope 1 has an inner diameter d and an outerdiameter D. The wall of envelope 1 comprises slits 4 and lids 5 that areshown here in several possible formats; for example, lid 5 formed acontinuous fold. Another possibility is represented in slit 4 a whereinlid 5 d is immobilized in one of its ends 5 a, to the envelope's walland at its other end moves freely in and out of a recess 7 formed in theopposite envelope's wall.

FIG. 17 a illustrates a longitudinal cross section of the implant'senvelope 1, containing integral step P and expander 20 inside itsbarrel. The envelope 1 comprises a slit 4, an apical inner diameter d,and a step P. The step P has a thickness of T_(Y), an angle θ, defininga slope of side L. Expander 20 is illustrated here as a conical shapedmember with a coronal base 20D_(C) and an apical base 20D_(A). FIG. 17 billustrates a schematic presentation of the same, wherein angle θ1 isbetween about 3 to 60 degrees.

FIGS. 18 and 19 illustrate a longitudinal cross section and perspectivelongitudinal cross-section of an implant 110. It is submitted that theimplant illustrated in FIGS. 18 and 19 are fully supported by thedescription provided above. FIGS. 18 and 19 include unique referencenumerals, however all of the features are disclosed in the Figs. andembodiments discussed above. Implant 110 includes a envelope 112including an outer surface 114 and an inner surface 116 defining abarrel 118. At least one barrier 120 is located in barrel 118. Thebarrel includes two regions 122 and 124 located on opposite sides ofbarrier 120. An expander 126 is movable within the barrel 118 from thefirst region 122 toward the second region 124. An inwardly extendingtransition region 128 extends between the first region 122 and barrier120. As expander 126 is moved from the first region 122 toward thesecond region 124 a portion of the envelope is forced radially outwardlyallowing expander 126 to move from the first region 122 toward thesecond region 124. The insert is shown in its contracted configurationin FIGS. 18 and 19. The insert moves towards it expanded configurationas the expander is moved from the first region 122 toward the secondregion 124. The diameter of the first region 122 is greater than thediameter of the second region 124 when the insert is in the contractedposition. Barrier 120 includes a step 130 having a ledge 132 extendingaway from the longitudinal axis of the insert. In one embodimentexpander 126 has a frustoconical shape as described above with respectto the expander 20. However expander 126 may also have a cylindricalshape as illustrated in FIG. 7.

Expander 126 may be moved within barrel 118 by a longitudinal member 134having a threaded portion 136 and a top portion 138. Longitudinal member134 is threadably received in insert 110 via an internal threaded region140. Internally threaded region 140 in one embodiment is locatedadjacent a coronal end 142 of insert 110. First region 122 may bethreadless as is expander 126. In the contracted configuration an upperedge 144 located at the top of expander 126 is located adjacent threadedregion 140. Longitudinal member 134 is threadably rotated withininternal threaded region 140 until a bottom 148 longitudinal member 134contacts the top of expander 126 and forces expander 126 toward thesecond region 124. A portion of envelope 112 radially expands outwardlyas expander 126 moves toward barrier 120 allowing an upper edge 144 ofexpander 126 to pass barrier 120. Once expander 126 passes barrier 120,the radially expanding portion may move toward the longitudinal axislocking expander 126 within the second region 124. The movement of theradially expanding portion may result from the spring bias of the insertand/or external pressure exerted upon the insert by the bore wall of apatient. Ledge 132 prohibits expander 126 from moving from second region124 toward first region 122. Longitudinal member 134 may then be removedindependent of expander member 126 and insert 110 remains in an expandedconfiguration as shown in FIGS. 6 c and 7 c. A tooth prosthesis can thenbe threadably received within the internally threaded region 140 tosecure the tooth prosthesis to the insert. In the expanded configurationthe bottom 152 of expander 126 is adjacent the bottom 150 of insert 110.The location of bottom 152 proximate the bottom 150 of insert 110provides a greater surface area for the insert in the bore of a patient.In one embodiment the length of the expander 126 as measured from thetop to bottom of the insert is substantially the same as the length ofsecond region 124.

Referring to FIGS. 6, 16, 18 and 19, top surface 144 of expander 126faces the coronal portion 142 and bottom surface 152 faces the bottom ofthe envelope 150. The bottom surface 152 of expander 126 has a diameterthat is less than or equal to the diameter of the bottom opening of theenvelope when the expander is in second region 124. The envelopeincludes a first non-radially expandable portion and a second radiallyexpandable portion extending therefrom. The bottom portion of the secondradially expandable portion extends radially further than the top end ofthe second radially expandable portion in the expanded configuration.The folded 146 portion having a top portion proximate the top end of thesecond radially expandable portion and a bottom edge proximate thebottom portion of the second radially expandable portion. In oneembodiment, the bottom surface of the expander is in the same plane as abottom surface of the envelope when the expander is in the secondregion. In another embodiment, the bottom surface of the envelope doesnot extend over a bottom most surface of the expander when the expanderis in the second region.

The radially expandable portion of insert 110 may include one or moreexpandable regions 146 formed arranged in a folded arrangement in thecontracted configuration. The expandable regions extend by unfolding orbecoming straighter as the insert is moved from a contractedconfiguration to an extended configuration. Expandable regions may alsoinclude a lid 5 d extending in a slit 4 as discussed above.

The construction and arrangement of the elements of the insert as shownin the various exemplary embodiments is illustrative only. Although onlya few embodiments have been described in detail in this disclosure,those skilled in the art who review this disclosure will readilyappreciate that many modifications are possible (e.g., variations insizes, dimensions, structures, shapes and proportions of the variouselements, values of parameters, mounting arrangements, use of materials,colors, orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited herein. Forexample, elements shown as integrally formed may be constructed ofmultiple parts or elements, the position of elements may be reversed orotherwise varied, and the nature or number of discrete elements orpositions may be altered or varied. It should be noted that the elementsand/or assemblies of the system may be constructed from any of a widevariety of materials that provide sufficient strength, durability, orbiocompatibility. The various features described herein may be usedalone or an any combination. For example, the use of a lid or thinwalled region may used in a conventional prior art insert or may be usedin conjunction with the barrier feature. Other substitutions,modifications, changes and omissions may be made in the design,operating conditions and arrangement of the preferred and otherexemplary embodiments and medical procedures without departing from thescope of the present invention.

What is claimed is:
 1. A dental implant system for placement within ajaw of a patient, the implant comprising; a dental implant having anenvelope including an outer surface and an inner surface defining abarrel, the envelope having a coronal end and an opposing bottom end;the coronal end of the envelope including a female threaded portion; anexpansion tool threadably received in the female threaded portion, theexpansion tool having a proximal end and a distal end; at least onebarrier located in the barrel at a predetermined location, the barrelhaving a first region on one side of the barrier and a second region onan opposing side of the barrier; an expander being positioned within thebarrel; the distal end of the expansion tool contacting a first side ofthe expander and moving the expander from the first region to the secondregion; the expansion tool being removable from the female threadedregion; a tooth prosthesis threadably secured to the female threadedregion; the envelope including a radially expandable portion beingradially expandable from a contracted configuration to an expandedconfiguration upon movement of the expander from each first regiontoward the corresponding second region, the radially expandable portionexpanding a predetermined distance as the expander is moved from thefirst region to the second region.
 2. The dental implant system of claim1 wherein the at least one barrier is a step having a ledge portionextending away from a longitudinal axis of the barrel.
 3. The dentalimplant system of claim 2, wherein the expander member is secured in adiscrete predetermined location by the step located within the barrel,the step allowing the expander member to move only in a singledirection.
 4. The dental implant system of claim 3, wherein the at leastone barrier is at least two steps.
 5. The dental implant system of claim4, wherein the expander member is adapted to be displaced along thelongitudinal axis in a number of discrete locations equal to the numberof steps.
 6. The dental implant of system of claim 5, wherein each stepis characterized by a side, depth, and angle defining a slope of theside.
 7. A dental implant system for placement within a jaw of apatient, the implant comprising; a dental implant having an envelopeincluding an outer surface and an inner surface defining a barrel, theenvelope having a coronal end and an opposing bottom end; at least twobarriers located in the barrel at predetermined locations, the barrelhaving a first region on one side of each barrier and a second region onan opposing side of each barrier; an expander member movable within thebarrel predetermined distances along a longitudinal axis of the barrelfrom the first region to the second region of each barrier, each barrierprohibiting the expander member from moving from each respective secondregion to the first region; a tooth prosthesis secured to the coronalend; the at least two barriers each including a step having a ledgeportion extending away from a longitudinal axis of the barrel; whereinthe expander member is secured in a discrete predetermined location bythe step located within the barrel, the step allowing the expandermember to move only in a single direction; wherein the expander memberis adapted to be displaced along the longitudinal axis in a number ofdiscrete locations equal to the number of steps; each step ischaracterized by a side, depth, and angle defining a slope of the side;wherein the envelope includes a radially expandable portion beingradially expandable from a contracted configuration to an expandedconfiguration upon movement of the expander from each first regiontoward the corresponding second region, the radially expandable portionexpanding a first distance as the expander is moved over the first step,the radially expandable portion expanding further as the expander ismoved over the second step.
 8. The dental implant system of claim 7,further including a longitudinal member being removably received througha coronal end of the envelope, the longitudinal member having sufficientlength to operatively move the expander member from each first region toeach second region.
 9. The dental implant system of claim 8, wherein theenvelope includes an internally threaded region proximate the coronalend of the envelope, the longitudinal member being threadably receivedin internally threaded region of the envelope, the longitudinal memberbeing removable independent of the location of the expander member. 10.The dental implant system of claim 9, wherein the tooth prosthesis isthreadably secured to the internally threaded portion upon removal ofthe longitudinal member.
 11. The dental implant system of claim 10,wherein the expander is threadless and a barrel portion through whichthe expander member moves is threadless, the barrel movingnon-rotationally from each first region to each second region.
 12. Thedental implant system of claim 11 wherein each first region is closer tothe coronal region than each second region, the expander member movingdownwardly along the longitudinal axis upon an application of force bythe longitudinal member, the barrier prohibiting the expander memberfrom moving from each second region toward each first region.
 13. Adental implant system, comprising a dental implant having an envelopeincluding an outer surface and an inner surface defining a barrel, theenvelope having a coronal end and an opposing bottom end the coronal endhaving a threaded region configured to receive a threaded portion of atooth prosthesis; a plurality of discrete barriers located in the barrelat predetermined locations, the barrel having a first region on one sideof each of the barriers and a second region on an opposing side of eachof the barriers; an expander member movable within the barrel to anumber of discrete positions proximate each barrier equal to the numberof barriers; the envelope including a radially expandable portion beingradially expandable from a contracted configuration to a fixed number ofdiscrete expanded configurations equal to the number of barriers uponmovement of the expander from the first region toward the second regionover each successive barrier, the radially expandable portion expandinga first distance as the expander is moved over the first barrier and agreater distance as the expander is moved over each additional barrier.14. The dental implant system of claim 13 wherein the plurality ofdiscrete barriers includes a step having a ledge portion extending awayfrom a longitudinal axis of the barrel.
 15. The dental implant of systemof claim 14, wherein each step is characterized by a side, depth, andangle defining a slope of the side.
 16. A method comprising; drilling abore within a jaw of a patient; providing a dental implant having acoronal end and an elongated envelope having a barrel defining alongitudinal axis extending longitudinally therethrough, the envelopehaving a radially expandable portion having a predetermined number ofbarriers located therein the coronal end having a threaded regionconfigured to receive a threaded portion of a tooth prosthesis; placingthe dental implant into the bore formed in a jaw of a patient; moving anexpander along the longitudinal axis across a first of the predeterminednumber of barriers forcing the radially expandable portion from a firstcontracted configuration to second predetermined expanded configuration,the expander being prohibited from moving back across the first barrier;wherein if the predetermined number of barriers is great than 1, thenrepeating the step of moving the expander across the successivepredetermined barriers, expanding the radially expandable portionfurther each time the extender is moved over each successive barrieruntil the radially expandable portion is at one of the desiredpredetermined expandable configurations.
 17. The dental implant systemof claim 16 wherein the at least one barrier is a step having a ledgeportion extending away from a longitudinal axis of the barrel.
 18. Thedental implant of system of claim 17, wherein each step is characterizedby a side, depth, and angle defining a slope of the side.
 19. A methodcomprising: drilling a bore within a jaw of a patient; providing adental implant including: an envelope including an outer surface and aninner surface defining a barrel, the envelope having a coronal end andan opposing bottom end, the coronal end including a female threadedportion; at least one barrier being positioned in the barrel at apredetermined location, the barrel having a first region on one side ofthe barrier and a second region on an opposing side of the barrier; anexpander being positioned within the barrel; a radially expandableportion being radially expandable from a contracted configuration to anexpanded configuration; providing an expansion tool separate from theexpander having a male threaded region and a distal end; threading theexpansion tool into the female threaded region, until the distal end ofthe expansion tool contacts the expander and the expander moves from thefirst region over the barrier toward the second region, expanding theradially expandable portion from the contracted configuration to theexpanded configuration; threadably removing the expansion tool from thefemale threaded region and the implant, the barrier prohibiting theexpander member from moving from the second region toward the firstregion upon removal of the expansion tool from the implant; andthreading a tooth prosthesis to the female threaded region.